Comcast is introducing a new high-end home security system this week, tapping its cable TV and Internet lines to give customers around-the-clock monitoring and control of their homes and utilities.

The company tested its new Xfinity Home Security service in Portland and Houston over the past several months and launches it Wednesday here and in six other cities. It plans to roll out the service elsewhere later this year, with monthly rates between $30 and $40.

The service sets up video cameras to allow customers to monitor their houses over Internet-connected computers. Subscribers can turn up the heat remotely or turn off lights; configure it so they get an email or text message when someone enters their homes; and manage their security and utility controls with their computer or iPhone.

"We are not just selling a security service," said Mitch Bowling, a Comcast vice president who manages the Philadelphia company's new businesses. "It's security coupled with home control."

Comcast's new security service was nearly two years in the making, according to Bowling. Its arrival comes as the cable industry stalls; Comcast shed 750,000 video customers last year.

Comcast intends to make it one of its central businesses, Bowling said, along with cable TV, phone service and Internet access.

Comcast is the largest cable TV company, both nationally and in the Northwest, running high-speed cable TV and Internet lines to 600,000 homes in Oregon and Southwest Washington.

The company is taking advantage of that network to try out new products, said Fred Christ, policy manager for the Metropolitan Area Communications Commission, which regulates cable TV service in Washington County.

"Obviously Comcast has a big pipe," Christ said. "Anything you can do (to use that technology), they're probably going to look into."

Comcast charges $30 a month for its basic service, along with a $200 installation fee. A more robust package, which includes the video cameras and hardware to manage your thermostat and lights remotely, is $40 a month, plus a $300 installation.

The home security industry is led by ADT, which has a $2.6 billion business and 6.3 million customers. It launched its own advanced home security service, ADT Pulse, last fall. It charges $400-$1,300 for installation, with monthly fees between $48 and $58.

A national monitoring network and long experience in security give ADT a leg up on Comcast, said spokesman Bob Tucker.

The control panel for Comcast's new Xfinity Home Security service.

"We've been in this space for a long time," he said. "We've been in business, as an alarm company, for 135 years."

While new security systems give homeowners more control, they also open a potential vulnerability should outsiders gain access to these home networks. Large companies, notably Sony, have recently fallen prey to outside attacks that stole customers' personal data.

Comcast is aware of such threats and encrypted every part of its home security network, according to Bowling.

"One of the primary criteria was having a secure security system," he said.

The Portland area is becoming a fertile testing ground for new technologies. ADT tried out ADT Pulse here before rolling it out nationwide in October.

Comcast has tested other new products here first, too, including a short-lived cell phone service. And Google has launched a succession of new products in Portland first, including the social recommendation service Google Places and its new social buying service, Google Offers.

In Comcast's case, Bowling said that his company picked Portland as a proving ground because of the experience and capabilities of its local staff, not because of the region's demographics.

"They are very operationally savvy," he said, with experience launching new products.

"That's what it takes to take something new and most rapidly make it consumer-ready," Bowling said.